November 2016 to April 2017 Climate Outlooks for Antigua and Barbuda

30 11 2016

Dale C. S. Destin |

The November 2016 to April 2017 climate outlooks are now available for Antigua and Barbuda. Our worst meteorological (Met) drought on record ended in September and remains that way. Moderate or worse Met drought is unlikely for the foreseeable future. It is, however, unclear what will happen with respect to rainfall over the next six months as there are equal chances of below, near or above normal rainfall. Meanwhile, warmer than normal mean temperature is likely to continue.

Drought Meter

Drought

The Met and agrometeorological (AgMet) droughts remain ended, notwithstanding near record low rainfall for October. However, the hydrological (Hydro) and socioeconomic (SE) droughts continue at slight levels or worse. The island-average of 46.2 mm (1.82 in) for October 2016 is the fourth lowest on record dating back to, at least, 1928 and the lowest since October 2000.

Projected rainfall for next 6 months

Looking forward – unfortunately there is no decisive information on what can be expected rainfall-wise. There are equal chances of below, near or above normal rainfall for November-January (NDJ), February-April  (FMA) and November-April. Given these and other forecasts, particularly the drought forecast, moderate or worse Met and AgMet droughts are unlikely. Meanwhile, the Hydro and SE droughts are not expected to undergo sustained worsening. The drought watches have been dropped.

The cold phase of El Nino Southern Oscillation (ENSO) – La Nina is evident although an episode cannot yet be declared. Further, the criteria and episode – five overlapping “seasons” of La Nina temperatures is unlikely to be met.

If you are in our part of the world – the Caribbean, a La Nina would be more than welcome. However, it is coming a bit late as the greatest positive impact on our rainfall occurs during the wet season, which will come to a close at the end of December.

Precipitation and temperature

Year-to-date, the rainfall for Antigua is almost one-and-a-half times more than all the rainfall for 2015. Further, it is the wettest January-October since 2013. Notwithstanding, we are still over 5 inches in the “red” relative to the long-term average of 952.8 mm (37.51 in).

Notwithstanding the low rainfall for October, there has been a general up-tick in rainfall since August. It is difficult to say at this time what can be expected to the upcoming months what quantity we will get as we have no climate signal. However, we are unlikely to have below normal rainfall.

It is now almost certain that Antigua will have near normal rainfall for 2016 – 1067 to 1321 mm (42 to 52 in). This is doubled the amount for last year – the driest year on record.

For the period November to April, above normal temperature is likely.

See the following links for the full outlooks: November 2016, November-January 2016, February-April 2017November 2016-April 2017Drought, 2016 Updated Hurricane Season Forecast.

The next set of outlooks will be available by December 7, 2016.





Potential Flooding Rainfall to End the Hurricane Season

28 11 2016

Dale C. S. Destin |

Satellite Image - Past 6 hrs Ending 11:45 UTC or 7:45 Local Time

Satellite Image – Past 6 hrs Ending 11:45 UTC or 7:45 Local Time

A surface low pressure system is expected to form near the northeast Caribbean and cause potential flooding rainfall across much of the Eastern Caribbean through Tuesday. Antigua and Barbuda is expected to see peak totals today – Monday.

The system could cause 25 to 100 mm (1-4 in) of rainfall, with locally higher amounts, from the Dominican Republic to Trinidad and Tobago. The epicentre of the rainfall is likely to be just south of Antigua or across the northern Windward Islands where the total could max-out above 100 mm (above 4 in).

North American  Mesoscale Forecast System (Model) Rainfall Accumulations - Nov 27-29, 2016

North American Mesoscale (NAM Model) Forecast System Rainfall Accumulations – Nov 27-29, 2016.

 

Globale Forecast System (GFS) Rainfall Accumulations for the Period Nov 27-29, 2016

Global Forecast System (GFS Model) Rainfall Accumulations for the Period Nov 27-29, 2016

With this type of rainfall, minor flooding is expected and moderate or worse flooding is possible. Hence, flash flood watches and warning may be required for a number of other areas over the next 12 to 36 hours.

This may be a fitting end to a very wet start to November. The month had a near record wet start across the Eastern Caribbean. In Antigua, some areas received upward 200 mm (8 in) during the first 10 days of the month. At the V. C. Bird International Airport, the rainfall stood at 143.5 mm (5.7 in) by November 10 – the third most on record dating back to 1928.

Rainfall Anomalies

Rainfall Anomalies for the Period Nov 1-10, 2016

With this type of rainfall, minor flooding is expected and moderate or worse flooding is possible. Hence, flash flood watches and warning may be required for a number of other areas over the next 12 to 36 hours.

This may be a fitting end to a very wet start to November. The month had a near record wet start across the Eastern Caribbean. In Antigua, some areas received upward 200 mm (8 in) during the first 10 days of the month. At the V. C. Bird International Airport, the rainfall stood at 143.5 mm (5.7 in) by November 10 – the third most on record dating back to 1928.

Recall also, that there were deadly floods and landslides across portions of St. Vincent during the early parts of the month.

The forecast rainfall for Monday is not a foregone conclusion but it is quite possible. If it were to materialized, this November would be one of the wettest on record for much of the Eastern Caribbean. In Antigua, it would be the wettest since Hurricane Lenny’s deluge of 1999 and be among the top 10 wettest Novembers of all time.

After the low, very cool northerly winds are expected to blow across the region. These will likely cause our coolest weather for the season and since February. Night-time temperatures could fall to below 19 °C (66 °F) Monday, Tuesday and Wednesday nights.

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